Subclavian artery aneurysm associated with absence of the ipsilateral internal carotid artery

A 48-year-old male presented with a rare subclavian artery aneurysm associated with absence of the ipsilateral internal carotid artery. The aneurysm was resected and replaced with a Gore Tex(R) artificial graft. Computed tomography, angiography, and cerebral blood flow findings suggest that defect of the right internal carotid artery occurred in the developmental stage. There was no past history of trauma, nor histological evidence of inflammatory or sclerotic changes in the aneurysmal wall. The two vascular lesions may have been influenced by a synchronous causative factor in his developmental stage.